116 BRITISH GRAPTOLITES. 



ward at once, so that a considerable portion of the apertural region of the sicnla is 

 visible in both aspects of the polypary. The crossing canals are horizontal. 



The thecse are about 2 — 3 mm. in length, and 



Fig. 70 c— Leptograptus grandis, Lapw. . - , ,„ , . , - 



MS. the apertures occupy more than one-halt the width 



of the stipe proximally, and from one-half to one- 

 third of the width in the more distal parts. The 

 Distal thecse. Enlargement of part of proximal thecse are distinctly mucronate. 



Affinities. — L. grandis is somewhat closely allied 

 to L. latus in point of size and in the width of the stipes, but differs in the character 

 of the proximal end, the more median origin of the stipes, and in having fewer thecse 

 in the same unit of length. 



Horizon and Locality. — Glenkiln Shales. 

 8. Scotland : Glenkiln Burn. 



Associates, etc. — L. grandis is a somewhat rare fossil in the Glenkiln Shales of 

 S. Scotland, where it occurs associated with Diplog. ? perexcavatus, Climacog. 

 bicornis, etc., etc. The best specimens known to us are in Lapworth's collection. 



Leptograptus latus, sp. nov. Plate XVI, figs. 5 a — e. 



Polypary several cm. in length, stipes comparatively rigid, widening rapidly 



from their origin to a maximum breadth of 1"4 mm., and diverging at a 



wide angle from a conspicuous sicula. Thecse twelve to fourteen in 10 mm., 



inclined at 10° — 25°, five times as long as wide, and free two-thirds to 



one-third of their length ; apertural margins concave when compressed, 



occupying about one third of the total breadth of the stipe. 



Description. — The polypary is characterised by the rapid widening of the stipes 



and the relatively great breadth finally attained. The stipes may be very gently 



curved at the proximal end, and may oven undulate slightly throughout their 



length, but there is a general absence of the pronounced curvature characteristic of 



most species of Leptograptus : the width near the proximal end is about "4 mm., 



widening within 5 cm. to the maximum breadth of 1'4 mm. 



The sicula has a length of 1*5 mm., and th. I 1 

 Fig. 71 a.— Leptograptus latus, sp. nov. . . 



apparently originates about - o mm. above the aper- 

 ture. Thecse l 1 , 1", and 2 1 and 2- have mucronate 

 ' -r-r-'v'" apertures. 



Reverse view. Enlargement of part of The free outer walls of the thecse appear almost 



PI. XVI, fig. 5 c. . . . ■ i i 



straight in some aspects, whereas m others they 

 appear markedly curved. Their inclination varies conspicuously in different parts 

 of the stipes; near the proximal end they are inclined at 10° and are in contact 

 for about one-third of their extent, but both the inclination and the amount of 



